Control apparatus, including an auxiliary power recovery turbine for turbo-supercharged engines



Dec. 23, 1952 A A. B. NEWTQN 2,622,390

CONTROL APPARATUS, INCLUDING AN AUXILIARY POWER RECOVERY TURBINE FOR TURBO-SUPERCHARGED ENGINES Filed Feb. 28, 1946 4 Sheets-Sheet l IN VENTOI? flL WIN 3. IVEWTU/V A. B. N EWTON Dec. 23, 1952 CONTROL APPARATUS. INCLUDING AN AUXILIARY POWER RECOVERY TURBINE FOR TURBO-SUPERCHARGED ENGINES Filed Feb. 28, 1946 4' Sheets-Sheet 2 lull lllllllllri IIIIIIIIIIIIIH AIIIIIIH RQR W MAIN R Z Nw N WM M ma m H w m V: B kw & I

Dec. 23, 1952 A. B. NEWTON 2,622,390

CONTROL APPARATUS. INCLUDING AN AUXILIARY POWER RECOVEPJ! TURBINE FOR TURBO-SUPERCHARGED ENGINES Filed Feb. 28, 1946 4 Sheets-Sheet 3 Dec. 23, 1952 A. B. NEWTON 2,622,390

CONTROL APPARATUS, INCLUDING AN AUXILIARY POWER RECOVERY TURBINE FOR TURBO-SUPERCHARGED ENGINES Filed Feb. 28, 1946 4 Sheets-Sheet 4 INVENTOR. fiLW/N 5'. NEWTON Patented Dec. 23, 1952 CONTROL APPARATUS, INCLUDING AN AUXILIARY POWER RECOVERY TUR- BINE FOR TURBO-SUPERCHARGED ENGINES Alwin B. Newton, Dayton, Ohio, assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Application February 28, 1946, Serial No. 651,007

8 Claims.

This invention relates generally to improvements in power plants of the internal combustion type and particularly as commonly employed for aircraft.

The invention has particular reference to the utilization of normally wasted power 'of internal combustion engines, as represented by the discharge of the exhaust gases as waste to the atmosphere. It is, of course, common practice to use a part of the power present in the exhaust gas flow for the operation of the turbine drivin the supercharging compressor which supplies the air for combustion to the engine, and it is for use with power plants of this design that my invention is best adapted.

I am aware of the fact that previous attempts have been made to successfully embody in a power plant a means for using the power of the exhaust gases, over and above that necessary for operating the turbo-supercharger, but it is the primary object of my present invention to provide an improved system or apparatus for this purpose, of a practical nature and well adapted to use in connection with the various controls necessary in such installations.

Another object is to provide improved control mechanism or systems for this purpose which afford the precision in adjustments necessary to prevent the building up of excessive exhaust back pressures on the engine, which would reduce the power thereof and defeat my purpose, and to prevent robbing the turbo-supercharger of the power necessary to adequately supply the engine with air for combustion, which would have the same efiect.

Still another object is to provide improved means for utilizing the power recovered in this manner to augment the power or the work done by the engine itself.

These and other objects I attain in the manner now to be set forth and claimed and in the course of the description reference is had to the accompanying drawing wherein:

Figure 1 illustrates diagrammatically the application of one form of my power recovery system to an internal combustion aircraft engine. having conventional turbo-supercharger and other control elements.

Figure 2 illustrates a slight modification of the system of Figure 1.

Figure 3 is a diagrammatic-a1 showing of another modification of my power recovery idea-s, illustrating the use of an auxiliary propeller for using the recovered power.

Figure 4 is a similar view, with some parts 7 2 omitted, showing a slight modification of the system of Figure 3 for using the recovered power.

Figure 5 is a view similar to Figure 1 but illustrating a modification of the control system for the power recovering means and showing the apparatus in greater schematic detail.

Figure 1 Referring now more particularly to Figure l of the drawing, I have illustrated therein, in a diagrammatical fashion, a complete aircraft power plant including an internal combustion engine It having a power shaft ll driving a propeller l2. Air for supporting combustion in the engine It is taken through an intake [3 and passes through a compressor I4, a conduit [5, an after cooler It, a conduit 11, a carburetor l8, a throttle i9, a conduit 20, a second compressor 2| andthrough an intake manifold system 22 into the engine. The compressor M is driven by a gas turbine 23 and together therewith forms a unit commonly known as a turbo-supercharger. The after-cooler It removes the heat of compression of the air supplied by compressor [4 and for this purpose receives fresh air through an intake '24, passes it in heat exchanging relation to the air flowing toward the engine, and finally discharges the cooling air from an outlet 25. The carburetor [8 mixes fuel with the air while the throttle [9 controls the supply of the combustible mixture thus formed, being here shown as adjusted by a hand control 26.

The compressor 2! is directly driven from the engine as indicated at 21 and in addition to adding compression to the gas mixture aids in distributing such mixture to all cylinders of the engine.

The supercharger compressor I4 is of the centrifugal type in which the rate of compression varies in accordance with its speed. The speed at which the turbine 23 operates thus controls the compression, or the pressure of the air supplied to the engine.

The turbine 23 is powered by exhaust gas from the engine l0, these gases being led from an exhaust manifold 28 of the engine through a conduit or duct 29 and discharged to impinge the buckets on the turbine wheel 30 through a nozzle ring 3!, the gases thus used being delivered through the wheel to atmosphere as indicated. There is also conventionally provided a discharge duct or outlet 32 in which is located a damperlike throttle valve 33. As the valve 33 is opened the gases may flow past 'it with less resistance than presented by the turbine and thus the posii the propeller 42.

tion of this valve precisely controls the amount of the gases diverted through the turbine, and the operating speed of the turbo-supercharger unit as a whole.

The valve 33 is positioned by a reversible. electric motor 34 through the linkage designated generally at 35 and the motor is in turn controlled and energized by an impedance network and electronic amplifier 35 under the primary control of a pressure sensing controller 31 connected by a duct 33 to the conduit [1, and a manually adjustable pressure selector 39. This entire control system may be similar to that disclosed in Daniel G. Taylor Patent No. 2,388,350,.

issued November 6, 1945. The system is also shown and described in greater detail in connection with Figure 5. So far as, the invention of Figure 1 is concerned, it may be simply stated that the amplifier 36 operates to adjust the valve 53, through the motor 34, to set the operating speed of the turbo-supercharger units I423 to provide for the supply of air to the engine of a pressure called for by adjustment of the manual selector 39, and maintains this selected pressure under control of the pressure responsive controller 31.

As thus far described, it will be understood that the turbine 23 uses but a part of the power or energy present in the exhaust gases discharged by the engine. This power, in excess of that required for the operation of the turbo-supercharger, is ordinarily wasted and it is the purpose of my invention to provide practical means for using this otherwise lost power.

To this end I provide a second or auxiliary gas turbine 43 having a bucketed wheel 4|, a nozzle ring 42, a nozzle box 43 and an intake duct 44 opening into said box. As here shown, the in take of this second turbine 40 is connected to the outlet 32 of the first turbine 23, on the downstream side of the valve 33. The turbine 43 thus receives exhaust gases not used by the turbine 23 and it will be obvious that the power present in these excess gases is utilized by the second turbine without materially interfering with the normal operation of the first.

The second or auxiliary turbine 40 may be used to drive any load device, or mechanism requiring power rotation but I prefer, as shown in the drawing, to use the recovered power to assist the engine l itself in its work. For this purpose the turbine 40 has its shaft 45 connected through a gear train 46 to the shaft II driving On the shaft ll an over-running clutch, designated generally at 47, of any conventional form, is placed and it selectively connects the gear train to this shaft. As thus arranged, the turbine may exert a driving force upon the shaft ll, augmenting the power of the engine, but should the shaft be running at a greater speed than the end speed of the gear train 46, the over-running clutch will allow the shaft to turn free of the gears. The latter condition may occur in starting the engine, or when the demand on the turbo-supercharger is such that the turbine 23 is using a large part of the total volume of the exhaust gases, leaving little for driving the second turbine 40.

Figure 2 turbine 45 has its intake 44 connected at 48 to h the exhaust conduit 29 between the engine I9 and the turbine 23 of the turbo-supercharger. In lieu, then, of the valve 33 previously described, a throttle or throttle valve 49 is arranged in the exhaust conduit 29 and is connected for operation by a motor 50 similar to that indicamd above at 34 and controlled in a similar manner. The position of this throttle 49 will obviously vary the admission of the exhaust gases to the turbine 23 and as the throttle is closed it will reduce the volume of the gases thus used and divert an increasing volume into the inlet of the auxiliary turbine 4!].

Another throttle or throttle valve 5| is provided in the intake 44 and its operating arm 52 is connected through a link 53 to a crank arm 54 swung by the motor 55. A spring 55 normally urges this second throttle 5| toward the open position shown against a stop 52a and the link 53 has a longitudinal slot 56 receiving a pin 51 by which it is connected to the crank arm 54. The crank arm 54 is connected to an operating arm 58 on the throttle 49 by a spring link 59 which may expand after the throttle 49 is fully opened, in which position the arm 53 comes to rest against a stop 60.

This linkage arrangement is such that the throttle 59 will first move to the full open position shown, with the throttle 5i full open, whereupon a further demand for supercharging of the engine will cause the motor 553 to continue in operation, attempting to further open throttle 49. At this time the arm 58 is against the stop and the spring link 55 can only lengthen. But the pin 5?, having previously moved along the slot without affecting throttle 5%, now reaches the end of the slot and such continued move ment of the arm 54 will now pull on the link moving throttle 58 towards closed position. Thus, the demand for increased. supercharger output met by a diversion of a greater volume of the exhaust gases to the'turbine 23, reducing the output of turbine 45. The reverse sequence of operation takes place as the demand on turbine 23 decreases, the throttle 5i first opening wide and then the throttle 4-9 gradually closing.

It will be apparent then that the auxiliary turbine 33 which, as shown, drives the propeller shaft 5 i through the gear train uses only that part of the total volume of exhaust gases not required by the turbine 23 for supercharging the engine and thus interferes in no way with proper maintenance of induction system pressures.

Figure 3 For convenience in the illustration and description of this modification of my invention, I have shown the power plant as arranged in the conventional nacelle E! on a wing 52 of a multi-engine aircraft, although it is to be understood that my invention may be adapted also for use upon single engine aircraft in which the power plant is arranged in the fuselage.

Only a part of the power plant is here shown, including an engine #33 arranged within a cowl.- ing 54 of the nacelle and arranged to drive a propeller 55. The turbine 65 of the turbo-supercharger is indieated as connected to an exhaust gas duct 57 and the speed of the turbine is controlled by a waste gate 59 located in an outlet 39 in the manner reviously described, this waste gate being positioned by the reversible motor it controlled in the smile manner motor 33 of Figure 1.

To make use of the power present in the exhaust gases not used by the turbine 66, I provide a second auxiliary turbine H having an intake Ha connected to the outlet 69 aforesaid. The bucketed wheel 12 of the turbine H is arranged for rotation by exhaust gases directed thereag-ainst by a nozzle ring 13 and has its shaft 54 arranged to drive a gear train, indicated generally at 75. Gbviously, the turbine Tl will thus utilize whatever volume of the exhaust gases is not needed by the turbine 66 and will rotate the gear train 75 at a speed depending on the relative demands of the supercharger, as called for by the control system, supplying engine 53 with air for combustion.

To utilize the power thus secured, I here provide an auxiliary propeller '56 which is journaled at the end of a swinging arm structure ll, pivotally mounted at is in the wing 52. The end gear train 15 is a bevel gear 13a which meshes with and drives a bevel gear is. Bevel gear as is, in turn, constantly meshed with a bevel gear 88 at the end of a drive shaft 85 extending along the length of the arm structure Ti, and at its outer end the shaft 8i drives the propeller 76 through similar beveled gears 82. The arrangement of the swinging arm structure I! is such that normally the auxiliary propeller it may be retracted or swung rearward and upward into a cavity in the underside of the wing 72 near its trailing edge, as indicated by the dotted lines. When it is desired to put the auxiliary propeller '55 into operation, as when the conditions are such that the auxiliary turbine '55 may be ex pediently put into operation to recover the power lost in excess exhaust gases, the arm structure 71 may be swung downward and forward to the full line position at which the propeller it will be supported beneath the wing and in the air stream. Any suitable conventional retraction gear (not here shown) may be arranged in connection with the arm ii for operating it as de scribed.

Gears 19, 79a, and 8% will remain in engagement at all times. Consequently, it is necessary to provide some means for preventing the turbine H being driven when the propeller 16' is in retracted position. To accomplish this, I have provided a selectively positionable flap valve 90 which, as will be obvious from the drawing, may be arranged to connect the outlet 69 with either the turbine l! or with an outlet 12a to the atmosphere. In the position shown, the flap valve 9c is in its lowermost position in which the outlet 12a is closed and all of the gas leaving the outlet 69 passes to the turbine H. The flap valve 99 is automatically operated by the retraction movement of the auxiliary propelle l6 by means of a bell crank lever 9! connected at one end to the valve 96 and connected at its other end through a spring link 92 to the arm H below its pivot '18. The arrangement, as illustrated, is obviously such that when the propeller it is swung to operative position the link 92 will oscillate the bell crank 9i and move the flap valve 90 to the position shown in the drawing at which it closes off the outlet 72a and connects the intake '52 with the exhaust gas outlet 5-9. On the other hand, When the arm 'i! is swung upwardly and rearwardly to retract the auxiliary propeller E6, the initial movement will pull upon the link 92 to oppositely operate the bell crank lever 9| and move the valve 99 upwardly to a position in which the turbine H is isolated from the exhaust gas outlet it and the exhaust gas outlet 59 is connected through outlet 12a to the atmosphere. This will result in all of the exhaust gas leaving the turbine 65 being by-passed to atmosphere so that the wheel 12 of the turbine ceases to turn. Further movement of the arm Tl toward its retracted position will have no other eifect than simply to stretch the spring link 92. While I have shown the auxiliary propeller I6 as located in a position in which it would be within the slip stream of the main propeller 65, it is to be understood that the auxiliary propeller I6 can be located outside of the slip stream. This is particularly desirable in the case of high altitude flight where larger effective disk area is desired.

It is to be understood, of course, that the auxiliary turbine ll may, if desired, receive gases from more than one engine, each separately controlled.

Figure 4 In this view, I illustrate a modification of the system shown in Figure 3, but wherein the engine 63, propeller (i5, turbine 66, exhaust duct 6], waste gate 68, outlet 69 and motor 10 are all identical with the previous description. There is also provided the second auxiliary turbine H driving the gear train 75 and powering the auxiliary propeller 16 supported on its arm TI in, exactly the same manner.

Here, however, I provide a third auxiliary turbine, designated generally at 83, having an intake conduit 84 leading to a junction with the intake Ha of the second turbine H. The turbine 33 includes a bucketed wheel 85 against which the exhaust gases are caused to impinge through a nozzle ring 85 and this turbine drives the main propeller 65 through a shaft 8? and gear train 58 in the same manner as that previously described with reference to Figures 1 and 2. An over-running clutch 89 is provided between the gear train 88 and the main propeller 65 to disconnect the gear train from the propeller when the engine speed exceeds the terminal speed of the gear train.

The junction between the respective auxiliary turbine intakes i2 and 8 is provided with a selectively positionable flap valve 95! corresponding to flap valve 95 of Figure 3. The flap valve 90 is arranged in this modification to connect the outlet 68 with either of the turbines. This valve 99 is automatically operated by the retraction movement of the auxiliary propeller 16 by means of bell crank M connected at one end to the valve 98, and connected at its other end through a. spring link 92 to the arm Tl below its pivot .18, just as in Figure 3. The arrangement as illustrated is obviously such that when the propeller I6 is swung to operative position the link 92 will oscillate bell-crank 9i and move the flap valve $8 to the solid line position at which it closes ofi the intake 84 and connects the intake 12 with the exhaust gas outlet 69. On the other hand, when the arm ii is swung upward and rearward to retract auxiliary propeller T6, the initial movement will pull upon the link 92 to oppositely operate the bell-crank til and move the valve 90 upwardly to a position in which the intake 12 is isolated from the exhaust gas outlet 68 and intake 8 3 is connected thereto.

It will be apparent from the foregoing that in this system the auxiliary power may be utilized either for driving the auxiliary propeller 16 or the main propeller 55, at the will of the pilot or engineer in charge of the aircraits flight. For example, it may be desirable to tie auxiliary is discharged to the rear.

turbine 03 to drive the main propeller 65 during low level flight at which time the propeller .65 may absorb the full power thus directed to it, Whereas when the aircraft ascends to the higher levels it may be desired to put into use the auxiliary propeller it to provide added propeller blade area for the rarefied atmosphere there encountered. Neither auxiliary turbine 'EI nor I2 will interfere with the operation of the other and only one is brought into play at any one time due to the automatic operation of the control valve 90. It may here be noted that in the case of multi-engine aircraft the exhaust gases from both inboard and outboard engines on either side may be conducted to a single auxiliary turbine if desired. .It is also to be understood that the auxiliary propeller is preferably located outside of the slip stream of the main propeller.

Figure 5 In Figure 5 I have shown a form of my invention in which the exhaust back pressure is maintained constant for any given value of the intake manifold pressure and for any selected induction pressure. This results in more accurate control of the turbo discharge pressure. As with the other figures, corresponding reference numerals are employed to indicate corresponding elements.

Inasmuch as the novel portion of the present invention involves cooperation with certain elements of the control apparatus for the motor positioning the waste gate of the main turbine, this control apparatus for this waste gate motor,

whichwas shown boxed-in in the previous figures,

is shown in somewhat schematic detail in the present figure.

Before referring to the control apparatus, the arrangement of the turbines in the present species will be considered. The auxiliary turbine 40, in this species, is by-passed by a conduit 93 leading from the conduit 44 which supplies gas to the turbine at. Located within this by-pass conduit 33 is a Waste gate 94 which is actuated by a lever arm 95 and is biased to closed position by a spring 96 engaging the operating arm 55.

A spring 55 in the present form biases the throttle valve 5i to closed position rather than to open position ,as in the form of Figure 2. A

motor arrangement generally indicated at 9'! is employed to position throttle valve 5! and waste gate 34 through a pair of links 03 and 98. The construction of the motor and the manner in which it positions the valves 5! and 34 will be described in more detail later.

It; is to be noted that in this form of the apparatus, the main turbine 3I as well as the auxiliary turbine 40 is so disposed that the exhaust gas The inlet I3 of the compressor I4 is disposed towards the front so that the air drawn into the turbine has a tendency to produce a forward movement of the aircraft. Similarly, the lower end of the waste conduit 93 associated with auxiliary turbine 40 is disposed so that the gas issuing from it is discharged to the rear. By disposing the various elements in the manner recited, an appreciable jet effect is obtained to aid the forward motion of the craft. While this disposition of the turbines has been illustrated only in connection with the form of Figure 5, it is to be understood that any of the turbines of the previously described figures may be so disposed.

Considering now the control apparatus for turbine 23 and referring first to the motor 34, this motor is shown as comprising a rotor II with which are associated two field windings I02 and I03. The motor is of the split phase type so that upon the current supplied to one winding being displaced with respect to that supplied to the other winding, the motor will rotate in a direction dependin upon whether the current through the one winding leads or lags that through the other winding. The rotor IN is connected through a ear train I 05 to the throttle Valve 33. In order to simplify the illustration, the motor is shown as connected directly through a rotatable shaft to the throttle 33 instead of through a link such as link 35, as with the. species of Figure 1. It is of course to be understood that the manner of connection of the motor to the throttle is not an essential feature of my invention. The gear train I05 is also connected to a slider I0: of a follow up potentiometer I03. The potentiometer comprises a resistor I00 with which the slider I0'i is in sliding engagement. The terminals of the windings I02 and I03, the opposite terminals of resistor I09, and the slider I 0? are connected to terminals on the motor housing corresponding to the terminals shown in Figure 1. In order to simplify the description, these terminals will not be referred to specifically by reference numerals and the various conductors leading to and from them will be considered as though the terminals did not exist, that is as though the conductors were continuous. This practice will be followed in connection with the other units of the apparatus.

The network and amplifier unit 36 comprises a transformer H5. This transformer comprises a primary winding I I6 and a plurality of secondary windings II! and H8. The secondary II! is connected to the motor field winding I02 through conductors II9, I20, I2I, and I22. A condenser I24 is connected between conductors I I9 and I20. This condenser serves to displace the phase of the current flowing through winding I02 by 90.

The winding H8 of transformer H5 is employed to supply power to an amplifier I26. This amplifier may be of any suitable type which supplies output current, the phase of which is dependent upon the phase of the input signal. A typical amplifier is that shown in the patent to Beers, 2,020,275. An amplifier particularly suitable for use in connection with my apparatus is shown in Figure 1 of the co-pending application of Albert P. Upton, Serial No. 437,561, filed April 3, 1942, now Patent No. 2,423,534.

The output terminals I28 and I29 of the amplifier are connected to the motor field winding I03 by conductors I2I and I30. The phase of the current supplied by amplifier I26 to winding I03 is reversed with reversal of the phase of the input voltage. Because of the condenser I24, the current supplied to winding I03 is thus either 90 ahead or 90 behind in phase with respect to that supplied to winding I02.

Also included with the network amplifier 36 is a potentiometer I32 comprising a resistor I33 and a slider I34. The resistor I33 is provided with a conductive bar I39 at its right-hand end and the slider I34 is normally in engagement with this conductive bar. The slider I34 is positioned by a velocity controller I36 which is connected by a flexible drive shaft I31 to the shaft of the turbine 23. The velocity controller I33 is effective whenever the turbine speed exceeds a predetermined value to move the slider I34 to the left by an amount dependent upon the time that the velocity exceeds such predetermined value. The

9 details of this velocity controller are shown in the aforementioned Taylor patent.

Associated with the potentiometer I32 is a transformer I40. This transformer comprises a primary winding I4I and a secondary winding I42. The secondary winding is provided with an intermediate tap I43. The resistor I33 is connected between the left-hand terminal of secondary winding I42 and the tap I43. The righthand terminal of resistor I09 of potentiometer I08 is connected by conductor I44 to the righthand terminal of secondary winding I42, while the left-hand terminal of resistor I09 is connected by conductor I45 to tap I43.

It will be noted that the two potentiometers u I08 and I32 together with the transformer I40 constitute a network analogous in many respects to a bridge. The sliders I01 and I34 constitute the output terminals of this network and a voltage appears across these sliders, the magnitude of which is dependent upon their relative positions. The network just described constitutes one of several series networks which collectively determine the voltage applied to the input of amplifier I26.

One of the additional networks is included within the pressure responsive controller 31. This controller comprises a potentiometer I50 which includes a slider I! and a resistor I52. The slider I5I is connected to two opposed bellows members I53 and I54. The bellows member I54 is connected by a conduit I56 to the conduit I1 which is in turn'connected to the inlet of carburetor I8. Bellows I54 is thus subjected to the induction system pressure. The bellows I53 is evacuated so that it is responsive only to atmospheric pressure. This bellows serves to compensate bellows I54 for the varying effect of atmospheric pressure on the latter. The slider I5I is accordingly positioned solely in accordance with the induction system pressure.

The resistor I52 is connected across a secondary I51 of a transformer I53. The transformer I58 comprises a primary Winding I59. The network constituted by secondary I51 and potentiometer I50 produces a voltage measured between slider I5I and the left-hand terminal of secondary I51.

A further network is included within the pressure selector 39. This network includes two potentiometers I6I and I62. Potentiometer I6I comprises a resistor I64 and a slider I65. The slider IE5 is connected to a knob I66 shown but not otherwise identified in Figure l. The potentiometer I6I serves as a pressure selecting potentiometer and as will appear more clear from a later portion of the description, the movement of the knob I66 in the counterclockwise direction to move slider I65 serves to increase the induction system pressure that is maintained by the apparatus.

The potentiometer I62 comprises a resistor I61 and a slider I68 and acts as a calibrating potentiometer.

Associated with potentiometers I6I and I62 is a transformer I69 which comprises a secondary winding I and a primary winding Ill. The opposite terminals of resistor I64 are connected to the opposite terminals of secondary I10, while the left-hand terminal of resistor I61 is connected to the lower terminal of secondary I10- and the right-hand terminal to a center tap of secondary I10. This center tap of secondary I10 is connected to a center tap of resistor I64 so as to cause the voltage drop across resistor I64 to be less aifected by the variations in current flow 10 therethrough due to the movement of slider I55. Considering now the control equipment for the auxiliary turbine 40, the motor 91 comprises a rotor I80 with which are associated field Windings I3! and I82. The motor is of the same type as motor 34, that is, the type in which the direction of rotation is dependent upon the relative phase position of the current supplied to windings I8I and I82.

The rotor I89 is connected through a gear train I54 to a cam shaft I85 carrying a pair of cams I85 and I81. Cooperating with the cams I95 and E61 are a pair of levers I83 and I99. The lever I55 has a cam follower roller I90 bearing against the cam I86, while the lever I89 has a similar roller I3I bearing against the cam I81.

The springs 55 and 96 serve to maintain the levers I 89 and I in cam-following engagement with the cams I81 and I36, respectively. The cam I81 is provided with a cam portion which increases in radius from a point a to a point b, proceeding in a clockwise direction. From point D the cam is of relative diameter. The cam I86 s. of uniform radius from point e to point d, these two points corresponding in angular position to points a and b on cam I81. From point a, to point e, the radius of cam I86 gradually increases, and from point 6 back to a point closely adjacent the point 0 the cam is of uniform radius again. It will thus be apparent that upon counter-clockwise rotation of cams I61 and I86 through the against the biasing action of spring 55. Upon the cams I86 and I81 moving to the position where points I) and d are in engagement with the contact rollers I9I and I90, valve 6| is in fully-open position, and since cam roller IIII is now engaging the portion of the cam I81 of uniform radius, continued movement of the cams in a clockwise direction results in no further movement of valve 5|. Such continued motion does, however, cause a counterclockwise rocking of lever I98 to move valve 94 towards open position. Thus, as the cams are rotated in a clockwise direction, valve 5I is first moved to open position and then the waste gate valve 94 is moved towards its open position. Reverse movement of the cams, of course, causes reverse movement of valves 5I and 94.

A transformer 200 comprises a primary winding 253i and two secondary windings 202 and 203. The secondary winding 203 is connected to the field winding I6I of motor 91 through conductor 205, conductor 206, condenser 201, and conductor 208. The condenser 201 serves to displace in phase by the current flowing through winding IBI. The winding I82 is connected to the output terminals of an amplifier 209. This amplifier may be of the same general type as amplifier I26. The amplifier 209 is supplied with power by secondary 202, the output terminals of which are connected to the power terminals of the amplifier.

The voltage applied to the input terminals of amplifier 209 is determined by a plurality of series connected networks in much the same manner as in connection with amplifier I26. One of these networks includes two potentiometers 2I0 and 2H. The potentiometer 2I0 comprises a slider 2I2 and a resistor 2I3. The potentiometer 2 comprises a resistor 2I4, and a slider 2I5. The slider 2 I2 of potentiometer 2I0 is positioned by a pair of opposed bellows 2 I1 and 2 I8. The bellows 2&8 is connected to the interior of the exhaust conduit 29 leading to the turbine 23. The bellows 2 ill is evacuated so as to respond to purely atmospheric pressure, thus acting to compensate bellows 2 I3 for the varying effect of atmospheric pressure on it. The slider 2E5 of potentiometer 2M is likewise positioned by a pair of opposed bellows 222 and 223. The bellows 222 is connected by a conduit 222 to the intake manifold 22 so as to respond to intake manifold pressure. Bellows 223 is evacuated and compensates the bellows 222 for variations in atmospheric pressure. The resistors 2 I3 and 2|4 of potentiometers 2H3 and 254 are connected to the opposite terminals of the secondary 228 of a transformer 22?. Transformer 22? comprises in addition tothe secondary 225 a primary winding 228.

The reference numeral 230 is employed to designate a further potentiometer comprising a resistor 23! and a slider 232. The slider 232 is connected to gear train I84 so as to be positioned by the motor 91. The potentiometer 23d constitutes a follow up potentiometer. The opposite terminals of resistor 23I are connected to the opposite terminals of a secondary 235 of a transformer 236 having a primary winding 23?.

A potentiometer 246 comprises a slider 25! and a resistor 242. The right-hand terminal of resistor 242 is connected by conductors 243, 244, and 225 to the slider I65, While the left-hand terminal of resistor 242 is connected by conductors 24% and 2M to the slider I63. It will be recalled that the sliders I65 nd IE5 constitute the output terminal of the network including potentiometers IISI and I62. The voltage appearing across this network is thus impressed across resistor 242. A variable portion of the voltage is introduced into the series of networks controlling the input voltage to amplifier 209.

While the transformers H5, I40, I53, I62, 239, 22? and 236 have been shown as separate transformers, this has been done to group the secondaries more closely with the equipment energized by them. In actual practice, the secondary windings could all be disposed on one or a small number of transformers. In any event, where more than one transformer is used, all of the primary windings should be connected to a common source of alternating voltage.

Operation of Figure 5 The voltage applied to the input terminals of amplifier I26 is determined, as previously noted, by a plurality of networks. The path through these networks may be traced as follows: from the lower input terminal 250 through conductor 25I, the slider I01, the network including potentiometers I08 and I32, slider I34, conductor 253, the left hand portion of resistor I52, slider I5I, conductors 254 and 247, the network including potentiometers I62 and I6I and conductors 245, 244, and 255 to the upper input terminal 256. It will be noted that conductor 245 is grounded at 25'! so that the amplifier terminal 256 is at ground potential. 7

In considering the operation of the system, it will be assumed that the upper terminal of secondary III), the left hand terminal of secondary I51, and the left hand terminal of secondary I42 are positive with respect to the opposite terminals of the respective secondaries during the same half-cycle as indicated by the legends appearing on the drawings. With the sliders in the position shown and during the half cycle being considered, the slider I0! is negative with respect to the slider I34, the left hand terminal of secondary I51 is positive with respect to the slider I5I, and the slider IE8 is negative with respect to slider IE5. Thus, the voltage output of the network constituted by potentiometers Hi8 and I32 and that of the network including potentiometers IBI and H52 is opposed by the network including potentiometer I50. It will be assumed that the relative values of these voltages are such that the voltages cancel each other out so that no voltage exists between the amplifier terminals 256 and 2'10. Under these conditions, no current is supplied to winding I33 and the motor is unable to rotate. It is assumed that under these conditions the throttle valve 33 is in intermediate position at which the air supplied to the induction system by the compressor I4 is sufiicient to maintain the desired induction system pressure.

Let it be assumed that the induction system pressure falls, thus necessitating a greater compressing action upon the part of compressor [4. The effect of this reduction in pressureis to cause slider I5I to move to the left with respect to resistor I52. This causes a greater voltage to exist between the left hand terminal of resistor I52 and slider I5I. Considering the half cycle just considered, the effect of this is to cause the input terminal 255 of amplifier I26 to become positive with respect to the input terminalififi during the half-cycle being considered. In terms of alternating current, this results in an alternating voltage of a predetermined phase being applied to the input terminals 250 and 256. This in turn causes amplifier I25 to supply an alternating voltage of a predetermined phase to the motor winding I03. The system is so designed that the phase of this current with respectto that supplied to winding I02 is such as to cause the throttle valve 33 to move towards open position to permit more exhaust gas to be supplied to the turbine 3i. Motor 34 in so'moving, causes slider I01 to move to the right; that is, towards the negative end of the resistor. This increases the output voltage of the network including resistor I68 which, it will be recalled, opposes the network including potentiometer I50. Thus, after the slider III! has been moved a predetermined amount corresponding to the change in induction system pressure, the system will again be balanced so that the throttle valve motor 34 will no longer be'operated. f

In the event of a rise in induction system pressure, the slider I5I is operated in the opposite direction with the result that the voltage supplied to input terminals of amplifier I26 is opposite in phase'to' that previously considered. Theefiect of this is to cause the amplifier I26 to supply'current to motor winding I33 which is likewise opposite in phase. This causes rotation of the motor IGI in the direction opposite to'that previously considered to cause the movement of the throttle valve 33 towards closed position and a movement of slider IiI'I of the follow uppotentiometer I08 towards the left.. Again, the movement of slider I0! isin a direction to rebalance the series of networks to cease operation of the motor 34. The operation of the rest of the control apparatus for motor 34 will not be described in detail; 'As previously mentioned, this apparatus is described in the above mentioned Taylor patent and for a clear understanding of the invention, reference may be made to that application. In general, a movement of the manually positioned slider I25 downwardly has th'e'same eifect upon theunb'alance voltage as the movement of slider I5I of the potentiometer I55 to the left; that is, to increase the compressing effect of compressor I4. Thus, movement of slider I65 downwardly by rotation of knob I66 in a counter-clockwise direction increases tion system pressure maintained by the system. The potentiometer I62, as previously noted, is used to initially calibrate the apparatus. Movement of the slider I58 to the right increases the induction system pressure and to the left decreases the same.

The velocity controller I55 is effective whenever the velocity of the shaft of turbine 23 rises above a predetermined value to move slider I34 to the left. The effect of this is the same in direction as that occurring when slider |I moves to the left. In other words, the movement of slider I34 to the left decreases the amount of exhaust gas supplied to the turbine 23 and hence decreases the speed of operation of compressor I4.

It will thus be seen from the above that the control apparatus for motor 35 serves to so position the throttle valve 33 that there is maintained in the induction system H, a pressure equal to that selected by the network including pressure selecting potentiometer I5I and calibrating potentiometer I522. The only exception to this is when the velocity controller I55 responds to the presence of an overspeed condition in which case, the speed of the compressor I l is reduced regardless of the demand of the rest of the system.

As previously noted, the species of this figure provides means for controlling the pressure in the exhaust conduit by supplying varying amounts of exhaust gas to the auxiliary turbine 25. The amplifier which controls the operation of motor 91 positioning valves 95 and 5| is controlled by a series of networks which may be traced as follows: from the lower input terminal 265 of amplifier 259 through conductor 25 I, the network including potentiometers 2H3 and 2H, conductor 262, the left hand portion of resistor 23!, slider 232, conductor 253, slider 25!, resistor 252, and conductor 255 to the grounded input terminal 265- of amplifier 259. The voltage applied to the amplifier 259 is thus the sum of the voltage output of the bridge including potentiometers 2I9 and 2| I, the voltage existing across the left hand portion of potentiometer 23I and the voltage existing between the slider 2M and the right hand terminal of resistor 242. It may be again pointed out at this point that the voltage existing across 242 is that determined by the output voltage of the bridge consisting of pressure selecting potentiometer I5I and calibrating potentiometer I52. The slider 2 is provided for the purpose of determining what portion of this voltage is introduced into the input circuit of amplifier 259. In considering the operation of the networks, the conditions during a half cycle will again be considered. The same half cycle will be considered as was considered in connection with the operation of amplifier I25. Thus, the voltage across the resistor 242 will be that indicated by the legends; that is, the right hand terminal of resistor 242 will be positive with respect to the left hand terminal. The primaries are so connected to the common source of power that during this half cycle, the left hand terminal of secondary 235 is positive with respect to the right hand terminal. Similarly, the left hand terminal of secondary 225 is also positive with respect to its right hand terminal. Considering first the bridge consisting of potentiometers 2 I0 and 2| I, it will be notedthat the two sliders 2I5 and 2I2 are centhe inductrally disposed with respect to their associated resistors and with respect to the secondary winding 229 so that no voltage exists between these two sliders. Considering now the effect of potentiometer 239, it will be noticed that conductor 252 is positive with respect to slider 232. The slider 232 is in turn connected to slider 2M which is negative with respect to the right hand terminal of resistor 252. The voltages introduced by p0.- ten-tiometers 235 and 245 thus oppose each other. It will be assumed that the value of secondary 255 is such that these voltages exactly balance each other so that no voltage is applied to amplifier 255. Under these conditions, the throttle valve 5| is partially open so that the turbine 40 is operating at partial capacity. Now let it be assumed that the pressure within the exhaust manifold rises either due to an increase in the supply of exhaust gas or to a decreased demand by turbine 3|. Under these conditions, the slider 2I2 will move to the left so that this slider becomes positive with respect to slider 2|5. The effect of this is to cause terminal 255 to become negative with respect to terminal 255. When this happens, the amplifier 259 is eiiective to supply to winding I82 an alternating current which is of such phase with respect to that supplied winding |5I that the motor 9? is effective to rotate the cams I85 and IS! in a counter-clockwise direction. The movement of cam E85 in a counterclockwise direction has no effect upon the cam follower I55 due to the fact that the portion of the cam engaged by it at this time is of uniform diameter. The motion of cam I51 in a counterclockwise direction, however, results in the lever its being rocked in a counter-clockwise direction to cause valve 5| to move towards open position. This permits more gas to flow to the turbine do to increase the power supplied by it to the main propeller I2. The increase in the amount of gas supplied to turbine 55 causes a decrease in the pressure within the exhaust gas conduit 29. At the same time, the slider 232 is moved to the left so as to tend to make terminal 255 less negative with respect to grounded terminal 255. Upon slider 232 moving sufiiciently to the left, the network will again be balanced, with the result that the motor 9'! is no longer energized in such a manner as to cause movement thereof.

Now let it be assumed that due to the change in position of valve 5| or for any other reason, the exhaust gas pressure within conduit 23 falls below the value which it is desired to maintain. Under these conditions, the right, causing terminal 255 of amplifier 259 to become positive with respect to grounded terminal 255. This causes a reversal in the phase of the voltage applied to the input terminals of amplifier 259 and hence a reversal in phase of the current supplied to winding I82. This causes motor 97 to operate in the opposite direction to move valve 5| towards closed position. At the same time, slider 232 is moved to the right to tend to make terminal 250 less positive with respect to terminal 255 and hence to rebalance the system.

Assuming again for the moment that the pressure in conduit 25 continues to rise, the valve 5| is progressively opened until it is completely open. At this time, the cam followers i55 and I9I will be in engagement with their respective cams at points (1 and b, respectively. Upon a further rise in exhaust gas pressure, it is necessary to provide for a greater escape from the conduit 29 if the exhaust gas pressure withslider 2I2 will move to in conduit 29 is to be maintained at the desired value. This is accomplished by the opening of valve at. As the cam I89 rotates in a clockwise direction beyond the point where cam follower I99 is in engagement with point d, the waste gate valve 84: is moved towards open position. This continues until point e is reached at which the waste gate valve 94 is fully open. Since the by-pass conduit as is open to atmosphere, the opening of waste gate 94 to even a relatively slight amount is normally all that is necessary to reduce the exhaust gas pressure within conduit 29 to the desired value. It is thus possible with the apparatus to insure a constant exhaust gas pressure within conduit 29 under all conditions. It is, of course, to be understood that normally the turbine) is able to utilize all of the exhaust gas that can be safely diverted from conduit 29 and it is only under exceptional circumferences that the gate 94 is moved towards open position.

It is desirable to increase the gas pressure within the conduit 29 when a higher induction system pressure is to be maintained. The reason for this is that in order to maintaina greater induction system pressure, assuming the atmospheric pressure to remain the same, it is necessary to have a greater exhaust gas pressure. It is for this reason that I apply a portion of the voltage across the network including the pressure selecting potentiometer [6i and the calibrating potentiometer IE2, to the amplifier 289. It will be recalled that this is accomplished by the potentiometer 249. The extent of this portion of this voltage that is applied to amplifier 299 is determined by the position of slider 2M. For any given position of this slider 24L if the pressure selector potentiometer I65 is changed by rotation of knob I65, the voltage existing between slider 24! and the right hand terminal of resistor 252 is likewise changed. F r example, assuming that the knob IE6 is rotated in a counter-clockwise direction to increase the induction system pressure that is maintained by the turbo supercharger control apparatus, the efiect of this will be to decrease the voltage existing between slider 2M and the right hand terminal of resistor 242. This will cause terminal 260 to become positive with respect to terminal 265 of amplifier 2539. The efiect of this, it will be recalled, is to cause motor 1-; to be energized in such a direction as to cause a clockwise rotation of cams l8? and 183. turn cause throttle valve 5| to move towards closed position to increase the pressure maintained within conduit 29. Again, the slider 232 will be moved to the left to decrease the voltage introduced by potentiometer 233. Upon a predetermined movement of slider 232, the series connected networks will again be balanced so that no voltage is applied to the input terminals 260 and 255. The system will now continue to operate to maintain a higher pressure within conduit 29 then previously existed.

In the present form, I have also provided means for decreasing the pressure which is maintained in the exhaust gas conduit 29! when the intake manifold pressure increases. An increase in intake manifold pressure indicates, all other things remaining unchanged, that the exhaust gas pressure is greater than necessary. The potentiometer 2i i is effective to introduce this compensation. Let it be assumed that there is a rise in intake manifold pressure. The effect of this is to cause the movement of slider 2-i5 to This will in the right which causes amplifier terminal 260 to become negative with respect to grounded terminal 235. This results in the motor 91 being operated in such a manner as to move the throttle valve 5i towards open position to increase the gas fiow through the auxiliary turbine 38 and hence to decrease the pressure within the exhaust gas conduit 29, assuming all other things remain equal. This will in turn tend to cause a decrease in the compressing eifect of compressor Id and hence a decrease in the intake manifold pressure. t will be obvious that a decrease in the intake manifold pressure has the opposite shoot; that is, of moving valve 51 towards closed position to increase the exhaust gas pressure within conduit as. In either the case of an increase .or decrease in the intake manifold pressure, the rebalancing potentiometer 235 is, of course, effective to rebalance the network.

It will be seen that with the arrangement of this figure, the auxiliary turbine is employed not only to obtain additional power that would otherwise be wasted but also to improve the operation of the main turbine control system in maintaining within the exhaust gas conduit a pressure such as to tend to cause proper operation of the turbine.

It will be obvious that numerous other modifications may be made within the spirit and scope of the appended claims.

I claim as my invention:

1. In a power plant, the combination with an engine having a superoharging compressor driven by a first gas operated power means actuated by exhaust gases from the engine and having aiconduit leading said gases to said first power means, of a throttle valve in said conduit for controlling the flow of exhaust gases through said first power means, a second gas operated power'means connected to the conduit to receive exhaust gases therefrom at the upstream side of said valve, a second valve for controlling the flow of exhaust gases through said second power means, a waste outlet connected to the conduit between the two valves, a third valve located in said waste outlet, and means responsive to exhaust gas pressures in the conduit for operating the second and third valves sequentially.

2. In a power plant, a combustion chamber, means for supplying a fuel mixture thereto, a first gas turbine powered by exhaust gas from the combustion chamber and having a conduit leading said gas from said combustion chamber to said turbine, a second gas turbine connected to said conduit, a compressor driven by said first turbine for supplying compressed air to said fuel mixture means, and means for controlling the pressure'of the air supplied to said fuel mixture means, said last named means comprising means responsive to the pressure of the gas in said conduit for varying the flow of gas therefrom through said second turbine to maintain a predetermined pressure in said conduit, and means responsive to the pressure of said compressed air for varying the flow of gas from said conduit through said first turbine.

3. In a power plant; a combustion chamber;

means for suppling a fuel mixture thereto; a

first gas turbine powered by exhaust gas from the combustion chamber'and having a conduit leading said gas to said turbine; asecond gas turbine connected to said conduit; a compressor driven by said first turbine for supplying .compressed air to said fuel mixture means; and means second pressure responsive means to vary the pressure of the air supplied to said fuel mixture means.

4. In a power plant; a combustion chamber; means for supplying a fuel mixture thereto; a first gas turbine powered by exhaust gas from the combustion chamber and having a conduit leading said gas to said turbine; a second gas turbin connected to said, conduit; a compressor driven by said first turbine for supplying compressed air to said fuel mixture means; and means for controlling the pressure of the air supplied to said fuel mixture means, said last named means comprising first pressure responsive means responsive to a power plant exhaust pressure for maintaining a predetermined pressure in said conduit by varying the fiow of gas therefrom through said second turbine, and second pressure responsive means responsive to the pressure of said compressed air for varying the flow of gas from said conduit through said first turbine, and third pressure responsive means responsive to the pressure of the fuel mixture for adjusting said first pressure responsive means.

5. In combination, a combustion engine having intake and exhaust conduits, a turbine driving a supercharger positioned in said intake conduit to supply compressed air to said intake conduit at a rate determined by the flow of gas through said turbine from said exhaust conduit, a carburetor, an engine driven compressor, means connecting said carburetor and said engine driven compressor in the order named between said supercharger and said engine in said intake conduit, first valve means positioned in said exhaust conduit between said engine and said turbine to vary the flow of gases through said turbine, first pressure responsive means responsive to the pressure in said intake conduit between said carburetor and said supercharger, means including said first pressure responsive means for varying the position of said first valve means to maintain a desired pressure between said carburetor and said supercharger, second valve means located in said exhaust conduit for by-passing the exhaust gases not needed by said turbine, second pressure responsive means responsive to the pressure between said second valve means and said first valve means, and means including said second pressure responsive means for varying the position of said second valve means to maintain a desired pressure between said second valve means and said first valve means.

6. In combination, a combustion engine having intake and exhaust conduits, a turbine driving a supercharger positioned in said intake conduit to supply compressed air to said intake conduit at a rate determined by the flow of gases through said turbine in said exhaust conduit, a carburetor, an engine driven compressor, means connecting said carburetor and said engine driven compressor in the order named between said supercharger and said engine in said intake conduit, first valve means positioned in said exhaust conduit between said engine and said turbins to vary the flow of gases through said turbine, first pressure responsive means responsive to the pressure in said intake between said carburetor and said supercharger, means including said first pressure responsive means for variably positioning said first valve means to maintain a desired pressure between said carburetor and said supercharger, second valve means located in said exhaust conduit for lay-passing the exhaust gases not needed by said turbine, second pressure responsive means responsive to the pressure between said second valve means and said first valve means, motor means positioning said second valve means in accordance with the pressure sensed by said second pressure responsive means, third pressure responsive means sensitive to the pressure between said engine driven compressor and said engine, and means including said third pressure responsive means for controlling said motor means.

7. In combination with a combustion engine having an engine driven compressor and an exhaust turbine driven supercharger operating in series with a carburetor in the engine manifold induction system so that air enters the engine through the supercharger, carburetor,- engine driven compressor, and manifold, sequentially, and an exhaust conduit with first valve means to regulate the flow of gases through the turbine of the supercharger and a by-pass valve means in addition to the first valve means to bypass the gases not needed by the turbine located between the engine and the turbine; control apparatus comprising first pressure responsive means sensitive to the pressure of the intake of the carburetor, a first actuator for positioning the first valve means, means operatively connecting said first pressure responsive means to said first actuator to maintain a desired pressure on the intake of the engine manifold, a manually operated pressure switch selector for adjusting the operative relation between said responsive means and said first actuator, a second pressure responsive means sensing the exhaust pressure between the by-pass valve means and the first valve means, a second actuator for positioning the bypass valve means, means operatively connecting said second pressure responsive means to said actuator, and means connecting said pressure selector to adjust the operative relation between said second pressure responsive means and said second actuator.

8. In combination with a combustion engine having an engine driven compressor and an exhaust turbine driven supercharger operating in series with a carburetor in the engine manifold induction system so that air enters the engine through the supercharger, carburetor, engine driven compressor, and manifold, sequentially, and an exhaust conduit with a control valve to regulate the fiow of gases through the turbine of the supercharger and a by-pass valve means in addition to the control valve to by-pass the gases not needed by the turbine and located between the engine and the turbine; control apparatus comprising a first actuator for positioning the control valve, first pressure responsive means sensitive to the pressure of the intake of the carburetor, means operatively connecting said first pressure responsive means in controlling relation to said first actuator to maintain a predetermined pressure on the intake of the carburetor, a manually operated pressure selector for variably adjusting the 19 operative relation between said first actuator and said first pressure responsive means, a second pressure responsive means responsive to the pressure in the engine exhaust conduit between the by-pass valve means and the control valve, a second actuator for positioning the by-pass valve means operatively controlled by said second pressure responsive means, means including said pressure selector for variably adjusting the operative relation between said second pressure responsive means and said second actuator, a third pressure responsive means sensitive to intake manifold pressure, and means including said third pressure responsive means for variably adjusting the operative relation between said second responsive means and said second actuator upon changes in intake manifold pressure.

ALWIN B. NEWTON.

REFERENCES CITED UNITED STATES PATENTS Name Date Moss July 28, 1931 Number Number Number Name. Date, 7 Smith June 10, 1941 Berger May 19, ,1942 Oswald 'Dec. 22, 1942 Morris Apr. 10, 1945 Silvester June 19, 1945 Lysholm Sept. 25, .1945 Birkigt June 25,1946 Planiol Nov. 19,1946 ONeil June 24, 1947 vBirmann Oct.,'14, 1947 Baak Nov. 23, 1.948 Sparrow June 21, 1949 Warner Aug. 30, 1949 Kutzler Dec. 13, 1949 Crum Jan. 3, 1950 FOREIGN PATENTS Country 7 Date Great Britain Feb. 11, 1 938 Great Britain Oct. 29, 1939 France Feb. 23, 1925 France Oct. 26, 1938 

